Metal losses and the heat-and-mass transfer in the working space of superpower arc steelmaking furnaces

The heat-and-mass transfer in the working space of an electric arc furnace (EAF) is analyzed on the basis of the real metal losses in industrial furnaces. The energy exchange between the arc discharge and the environmental space of the surface filled with the radiating and absorbing vapor-dust-gas medium is shown to change. The processes of metal evaporation and vapor condensation in the working space of EAF are considered.     

Evaporation of iron during steelmaking in arc furnaces

The problems of iron evaporation during steelmaking in an arc steel-melting furnace are considered. A procedure is developed for the calculation of the specific iron evaporation rate and the heat losses during evaporation. More complete absorption of the heat of condensation by a charge and the oxidation of iron vapors are shown to be promoted by the following factors: the presence of a slag coating, a decrease in the well diameter, an increase in the well depth, an increase in the electrode failure diameter, and directional supply of an oxidizer to the near-electrode zone.     

Conversion of arc steelmaking furnaces into plasma furnaces

Chelyabinsk Girpomez. Translated from Metallurg, No. 8, pp. 29–30, August, 1988.     

Effectiveness of using oxygen-gas burners in modern arc steelmaking furnaces

Oxygen-gas burners have become a standard component of modern electric-arc steelmaking furnaces worldwide as a means of increasing productivity and reducing electric power consumption. The use of such burners in these furnaces is expedient from both an economic and an energy standpoint. On the average, the use of 1 m³ of natural gas to heat the scrap in the furnace charge saves 0.6–0.8 m³ of natural gas for the refining operation. The amount of heat obtained from the combustion of natural gas can be increased significantly by equipping arc steelmaking furnaces with high-capacity rotary oxygen-gas burners that allow changes to be made to the direction of the flame.     

Heat losses and energy efficiency of arc steel-melting furnaces

The dependences of the heat loss power and the energy efficiency of arc steel-melting furnaces with a refractory lining on the arc current and length are analyzed. The influence of varying the heat loss power on the operating characteristics of an arc furnace is considered.     

Some metallurgical aspects of steelmaking with sponge iron in electric arc furnaces

Test charges containing sponge iron proportions varying from 38.7–95.4 wt% of the metallic input were melted in a UHP electric arc furnace with a design capacity of 70 tons per heat. After melting started, samples of molten metal and the corresponding slag were taken simultaneously at different time intervals and analysed. The time dependence of the chemical composition of the metal and slag as well as the variation of the temperature of the melt with time are given. Thermodynamic calculations using different methods for finding the activity of ferrous oxide show that there is a linear relationship between a_(FeO) and the total ferrous oxide content in the slag. It is also found that the total ferrous oxide content in the slag and the oxygen concentration in the metal vary linearly with the iron proportion from sponge iron in the metallic input. The activity of ferrous oxide decreases with increasing slag basicity due to the formation of calcium ferrites. The relationship between the oxygen concentration and the reciprocal of the carbon content in liquid steel is almost linear. A formula showing the influence of some important factors on the oxygen content in molten steel is given. The effect of sponge iron on the sulphur concentration in the steel is also investigated. The present results indicate that the sulphur content in the steel can be reduced from 0.02 to 0.004 wt% by increasing the iron proportion from sponge iron in the metallic input from 35 to 95 wt %. Using the boundary layer diffusion model, it is found that the rate of decarburization of a steel bath is enhanced by increasing the sponge iron proportion in the metallic input. The activation energy of the decarburization reaction is found to be 56.9 kJ/mol and the mass transfer coefficient of carbon has a value of 0.0161 cm/s at 1 600°C. In a way similar to that used for decarburization, it is also found that the rate of oxidation of manganese dissolved in the bath is enhanced by increasing the sponge iron proportion in the metallic input.     

Reducing metal losses when smelting steel in high-power arc furnaces

The heat transfer in arc furnaces with high input power is considered, in the case of induced slag foaming. Most of the power is consumed in evaporation of the metal and slag at hot spots under the electrodes and in zones of oxygen injection.     

Promising trends in improving steelmaking and finishing in ac electric arc furnaces and ladle-furnace units

The results of laboratory and full-scale tests performed to reveal the factors that affect the appearance of a constant arc voltage component (CAVC) in an arc steel-melting furnace (ASF) and an ladle-furnace unit (LFU) are presented.     

Energy saving for steelmaking in plasma-arc furnaces

A design for a plasma-arc steel-melting furnace with four plasma generators and a rational method for steelmaking, which can decrease the heat time and the electric energy consumption, are pro- posed. The rational arrangement of wall plasma generators in the liquid stages of a heat are determined by analytical investigations.